Subject: Re: Dual SCSI, single chain?
To: None <>
From: der Mouse <mouse@Rodents.Montreal.QC.CA>
List: port-alpha
Date: 03/15/1999 12:39:36
> I guess it's more a curiosity.  Does anyone know if it would be possible to
> run the following scenario?:

> 	Interal narrow SCSI controller connected via a converter
> 		to a wide chain.
> 	A good PCI wide SCSI card connected to the same wide chain.
> 	A wide SCSI drive operating off of the wide chain (and,
> 		via the converter, the narrow chain as well).
> 	Default SCSI id of 7 for one of the adapters, and perhaps
> 		a SCSI id of 6 for the secondary adapter.

Um, if the "good" SCSI card is wide, its default ID will be 15, not 7.

If you can keep the wide SCSI card from probing ID 7, I can't see any
reason this wouldn't work.  It might work even without that.

Termination might be a little tricky; the wide<->narrow adaptor will
need to deal with this, and I don't know how good they are.  I'm not
entirely clear on how arbitration works, but it seems to me there might
be trouble if it's possible for the narrow card to think it owns the
bus because it doesn't see a wide device on ID>7 (the wide card,
probably) asserting bus-ownership rights.

All that aside, this strikes me as a Pretty Neat Hack. :-)

					der Mouse

		     7D C8 61 52 5D E7 2D 39  4E F1 31 3E E8 B3 27 4B